Postage stamps

ABSTRACT

A stamp (1) is disclosed which has a luminescent coating (9, 11) which over the area of the coating is such that there are a plurality of coated spaced regions interspersed with non-coated regions. The coating may be applied as a grid or cross hatching or other suitable arrangement. The coating is applied over an area which is of sufficient size relative to the thickness and density of the coating to permit the coating to be detected by a postage stamp luminescence detection device. The non-coated regions over which the coating extends being of sufficient area to permit penetration and drying of a stamp cancelling ink. A method of producing such stamp is also disclosed.

FIELD OF THE INVENTION

This invention relates to postage stamps.

DESCRIPTION OF PRIOR ART

Hitherto, postage stamps with a pressure-sensitive adhesive on a rearface have been known. An example of a stamp of this nature is disclosedin International patent Application No. PCT/AU91/00200 in the name ofAustralian Postal Corporation trading as Australia Post. Thisspecification has been published under International No. WO 91/18378.The same stamp has been protected by way of Australian Petty Patent No,611625. The subject matter of those patent specifications is importedherein by reference,

Basically postage stamps with a pressure-sensitive adhesive are known bythe general term peel and stick stamps as they are carried on a backingsheet and can be peeled therefrom and applied with thepressure-sensitive adhesive to a postal article. Some of the knownpostage stamps include a water-soluble layer between the rear face ofthe stamp and the pressure-sensitive adhesive. The water-soluble layeris provided to permit the stamp to be recovered from a postal article bysoaking in water. The water thus penetrates the stamp and dissolves thewater-soluble layer thereby enabling the stamp to be recovered from thepostal article whilst leaving the pressure sensitive adhesive behind.

Stamps of the peel and stick type can be produced on a paper whichitself does not have a luminescent coating such as a phosphor coatingthereon or phosphor embedded therein. Thus, in order for such stamps tobe detected by a luminescence detection means at a mail centre it hasbeen necessary to coat the front surface of the stamp with luminescentmaterial such as phosphor. In the past, this has been achieved by theuse of a band of phosphor varnish printed across approximately one halfof the stamp. The phosphor varnish, however, is both non-waterpenetrable and non cancelling ink penetrable. Therefore, two problemsexist:- b 1. If a stamp is to be recovered from a postal article, watercannot penetrate the luminescent material coating and thus removal ofthe stamp is exceedingly difficult. 2. The approved post office securitycancelling inks are unable to penetrate and dry on the luminescentcoating.

It is not sufficient to merely reduce the area of the stamp cover by theluminescent material to enable water penetration as the problem isfurther complicated because with the known techniques of applying aluminescent material such as a phosphor varnish coating, the coatingthickness is generally insufficient for luminescence detection if only asmall area is applied to the stamp to enable subsequent recognition atthe mail centre. Typically, the varnish is applied by a lithographicprinting process and this results in a relatively thin coating appliedto the stamp. Accordingly, it has been necessary to repeat the printingprocess several times to provide the necessary thickness and density ofphosphor to enable satisfactory detection.

With known gum adhesive type postage stamps, the stamp material isitself suitably detection coated so that the approved post officesecurity cancelling inks can penetrate the surface of the stamp and dry.Thus, for known gum adhesive type stamps there has not been a problem inrelation to detection as the coating has been carefully chosen to havethe required detection and cancelling ink penetration and dryingproperties. Such paper is quite expensive and in Australia, and someother countries, the suitable detection coated paper must be imported asstock for the stamp printers. Accordingly, stamp printers and postalauthorities have desired to use a cheaper paper but there has been theproblem of how to economically apply a suitable luminescent coating tothe face of a stamp of such cheaper paper and at the same time permitthe stamp to be detected by the known luminescence detection devices,and still be able to enable the known cancelling inks to penetrate thecoating and to dry.

OBJECT AND STATEMENT OF INVENTION

Accordingly, it is an object of the present invention to attempt toovercome one or more of the aforementioned problems.

In accordance with a broad aspect of the present invention there isprovided a postage stamp comprising a stamp material carrying a stampimage on a front face and an adhesive on the rear face, the front facehaving a luminescent coating which over the applied area comprises aplurality of coated spaced regions interspersed with non-coated regions,the applied area being of sufficient size relative to the thickness anddensity of the coating to permit the coating to be detected by a postagestamp detection device and the non-coated regions being of sufficientarea to permit penetration and drying of a stamp cancelling ink.

In accordance with a further broad aspect of the present invention thereis provided a method of producing a postage stamp to permit detection bya postage stamp luminescence detection device and to permit penetrationand drying of stamp cancelling ink comprising:

(a) providing a stamp material;

(b) providing a stamp image to a front face thereof;

(c) providing an adhesive on the rear face;

(d) applying to the front face of the stamp a luminescent coating sothat over the applied area there are a plurality of coated spacedregions interspersed with non-coated regions, the applied area being ofsufficient size relative to the thickness and density of the coating topermit the coating to be detected by a postage stamp luminescencedetection device, and the non-coated regions being of sufficient area topermit penetration and drying of stamp cancelling ink.

In accordance with a further broad aspect of the present invention thereis provided a postage stamp of a stamp material with a stamp imagecarried on a front face thereof, and on the rear face a water-solublecoating and on the rear of the water-soluble coating apressure-sensitive adhesive coating,

the front face having a luminescent coating which over the area appliedcomprises a plurality of coated spaced regions interspersed withnon-coated regions, the applied area being of sufficient size relativeto the thickness and density of the coating to permit the coating to bedetected by a postage stamp luminescence detection device and thenon-coated regions being of sufficient area to permit penetration anddrying of stamp cancelling ink and to subsequently allow waterpenetration for dissolving the water-soluble coating if the stamp is tobe removed from a postal article.

In accordance with a further broad aspect of the present invention theremay be provided a postage stamp as previously defined adhered to arelease carrier backing by a pressure sensitive adhesive coating, so itcan be released therefrom to be applied to a postal envelope by adheringthereto with the pressure sensitive adhesive coating.

In accordance with a further broad aspect of the present invention theremay be provided a method of enabling a postage stamp to be detected by apostage stamp luminescence detection device, to permit penetration anddrying of stamp cancelling ink, and to enable water penetration if thestamp is to be removed from a postal article comprising:

(a) providing a stamp material;

(b) providing a stamp image to said stamp material on a front facethereof;

(c) providing a water-soluble coating to the rear face of said stampmaterial;

(d) providing a pressure sensitive coating to the rear of thewater-soluble adhesive coating;

(e) applying to the front face of the stamp a luminescent coating sothat over the applied area there are a plurality of coated spacedregions interspersed with non-coated regions, the applied area being ofsufficient size relative to the thickness and density of the coating topermit the coating to be detected by a postage stamp luminescencedetection device, and the non-coated regions being of sufficient area topermit penetration and drying of stamp cancelling ink and tosubsequently allow water-penetration for dissolving the water-solublecoating if the stamp is to be removed from a postal article.

Most preferably, the luminescent coating is applied as a phosphorvarnish and it is preferable that it is applied as a stipple, therebyproviding an arrangement of coated regions with interspersed non-coatedregions. Alternatively it may comprise a fluorescent coating.Preferably, the stipple is applied as dots in a regular arrangement.

It is particularly preferred that the phosphor coating is applied by aletter press process.

BRIEF DESCRIPTION OF DRAWINGS

In order that the invention can be more clearly ascertained examples ofpreferred embodiments will now be described with reference to theaccompanying drawings wherein:

FIG. 1 is a front view of a conventional peel and stick postage stamp ofthe type described in the aforementioned patent applications;

FIG. 2 is a diagrammatic view showing a prior art phosphor detectiondevice used for detecting the presence of postage stamps on an envelope;

FIG 3 through 5 are front views of examples of postage stamps producedin accordance with the present invention;

FIG. 6 is a cross-sectional view taken through a stamp according to thepresent invention; and

FIG. 7 is a perspective view showing a booklet incorporating thepreferred postage stamps.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to FIG. 1 there is shown a prior art peel and stickpostage stamp of the type disclosed in the aforementioned InternationalPatent Application No. PCT/AU91/00200. Here a stamp 1 is produced on asuitable stamp paper. The stamp 1 has a stamp image 3 on a front facethereof. The rear face of the stamp 1 is provided with a water-solublecoating and on the rear of the water soluble coating there is applied apressure-sensitive adhesive coating. Typically, the stamp 1 is carriedon a release backing (not shown) and can be peeled therefrom with thepressure sensitive adhesive intact on the rear of the stamp 1 so thatthe stamp 1 can be applied and adhered to a postal article by thepressure-sensitive adhesive. The peripheral edge of the stamp issuitably contoured, if required, to simulate perforations of aconventional perforated gum stamp. The aforementioned InternationalPatent Application No. PCT/AU91/00200 makes particular reference to thecontour of the peripheral edge of such stamp.

The front face of the stamp 1 has a detectable luminescent coating 5 inthe form of a solid phosphor varnish which extends over a considerablesurface area of the front face of the stamp 1. In the embodiments shownit extends across the height of the stamp and covers approximately adistance of about one half to one third of the length of the stamp. Theluminescent coating has been applied by a lithographic press printingprocess using a suitable phosphor varnish as a printing medium.

In use, an envelope with a stamp thereon is received at a mail centreand delivered to a known device for detecting the presence of a genuinestamp and for cancelling that stamp. The device is arranged to receivethe envelopes in an inverted form as shown in FIG. 2. A luminescencedetection window 7 of approximately 23 mm in height is spaced so thatthe uppermost edge is 40 mm from the base of the device and so that theapproximate centre of the window 7 is about 26 mm from the base. Thewindow, in turn, overlaps the position of a stamp as an envelope andstamp are moved therepast.

In order to provide for satisfactory detection by the detection device,it has been necessary to apply the phosphor varnish coating over asubstantial portion of the area of the stamp face as disclosed in FIG.1.

Several problems have occurred in relation to stamps with a phosphorcoating 5 which extends over this relatively large area of the stamp.Firstly, philatelists who wish to recover used stamps from a postalarticle, have been unable to readily recover the stamp as thewater-soluble adhesive or layer has not been able to be wetted in theregion where the phosphor varnish coating 5 is applied. This is becausethe phosphor varnish coating is generally water-impervious. In addition,water is unable to reach the water-soluble adhesive or coating from theundersurface of the envelope as the pressure-sensitive adhesive providesa further barrier. Thus, the stamp can be permanently disfigured duringthe recovery from a postal article. Thus, philatelists find it difficultto accept peel and stick stamps of this type. Secondly, the coating 5 issuch that it does not permit penetration and drying of the approvedstamp cancelling inks. Thus, it has been difficult to correctly andreliably cancel stamps of this nature.

Referring now to FIG. 3 there is shown an example of one preferredembodiment of the present invention. Here, the postage stamp 1 is of thesame peel and stick type as shown in the embodiment of FIG. 1. Thus, itis produced generally in accordance with the disclosures in theaforementioned International Patent Application No. PCT/AU91/00200.

The front face of the stamp 1 is covered with a luminescent coatingpreferably a phosphor varnish coating over selected regions 9 and 11. Inthe embodiment shown in FIG. 3 the selected regions comprise an upperhorizontal region 9 and a lower horizontal region 11 which extend thelength of the stamp. The coatings in the regions 9 and 11, over the areaof the applied phosphor varnish are such that there a plurality ofcoated spaced regions interspersed with non-coated regions. It isparticularly preferred that the coating be applied as a stipple whichwill provide a plurality of coated spaced regions interspersed withnon-coated regions.

Other arrangements for coating which provide for a plurality of coatedspaced regions interspersed with non-coated regions may compriseapplying the phosphor coating in a grid arrangement or a cross-hatchedarrangement. Any arrangement would appear to be satisfactory providedthere are a plurality of coated spaced regions interspersed withnon-coated regions. In the case where the coated regions are provided bya stipple coating, the percentage area of the stipple can be varied tosuit the thickness and density of the phosphor of the coating which isapplied. In other words, the coating must present a sufficient surfacearea for the density of the coating, to be detected by the window 7 inthe luminescence detection device. In the case where the coating isapplied by a sheet-fed letterpress, the coating will typically be in theorder of about 7.5 microns thickness. Thus, in this case, each of theregions 9 and 11 can have an approximate 80% cover of stipple varnishcoating of a composition to be described. The remaining approximate 20%being uncoated. Thus, in the example shown in FIG. 3 where the height ofeach of the regions 9 and 11 is in the order of 4 mm, and applied over agenerally white background, an approximate 80% cover of a suitablestipple phosphor varnish applied by a sheet-fed letterpress will givesatisfactory detection results. Other percentage areas may be entirelysatisfactory. For example, in order to determine a satisfactorypercentage area cover it is necessary to conduct some experimentationhaving regard to the thickness and density of the coating applied, thespacing or percentage cover of the varnish applied and the reflectivequalities of the surface over which the varnish is applied and, finallythe transverse length of the exposed surface of the coating which ispresented across the length of the window 7, i.e. the width of theregions 9 and 11 from top to bottom of the stamp. In practice, a balancemust be achieved between the surface area of the stipple--providing theplurality of coated spaced regions interspersed with non-coatedregions--to achieve the required detection whilst, at the same time,permitting penetration and drying of an approved cancelling ink, overthe regions 9 and 11, and water penetration which may be required whenthe stamp is to be released from a postal article. Thus, the permeationsof thickness and density of phosphor, cross-sectional area available,reflectivity of the surface of the stamp 1 and the exposed length of thephosphor coating to the detection window 7 need be considered.

Referring now to FIG. 4 there is shown an embodiment of a furtherpreferred stamp similar to that in FIG. 3 where in addition to providingthe coating over regions 9 and 11 a coating band is applied over region13 at one end of the stamp. Thus, a greater length of the coating can beprovided across the detection window 7.

In FIG. 5 there is shown a stamp 1 similar to that in the previousembodiments except that the coating is applied over the whole of thesurface area of the stamp 1.

In an embodiment not shown, the coating may be applied over selectedregions such as the regions shown or, alternatively over discreteportions of the stamp image such as on the animal 15 shown in FIG. 4.Thus, in future, stamps may need to be designed carefully to take intoaccount the image on the stamp and the coating regions.

Thus, in all cases, the coating is applied over an area of the stamp toprovide a plurality of coated spaced regions interspersed withnon-coated regions and where over the applied area the coated regionsare of sufficient size relative to the thickness and density of thecoating to permit the coating to be detected by a postage stampluminescence detection means, and the non-coated regions being ofsufficient area to permit adhered application of stamp cancelling inkand to subsequently allow water penetration for dissolving thewater-soluble coating if the stamp is to be removed from a postalarticle.

Preferably, the phosphor varnish coating for the embodiments above isformulated in accordance with the following formula:

2 parts matt varnish--supplied by Collie Cook Consolidated of GracieStreet, North Melbourne, Victoria, Australia

1 part HELECON 336, phosphor--supplied by Chemical and PetroleumIndustries of 20 Ponting Street, Williamstown, Victoria, Australia

Referring now to FIG. 6 there is shown a transverse cross-section takenthrough a preferred postage stamp embodying the present invention. Hereit can be seen that the stamp 1 is produced by two substrates 17 and 19.Substrate 17 is preferably of a coated paper of 80 gsm such as Redanmanufactured by Australian Pulp & Paper Mills, Marine Terrace, Burrile,Tasmania, Australia. It comprises an upper clay coating 21, a base paper23, a water-soluble layer 25. The substrate 19 is suitable backingmaterial such as siliconized backing of any suitable material. Suitablesubstrates 19 are glassinc, kraft and coated backing papers. Suitablematerials can be supplied by Consolidate Paper Industries, Mills Road,Braeside, 3195, Victoria, Australia and Jac Australia Pty Ltd of 663Chapel Street, South Yarra, 3141, Victoria, Australia. Substrate weightis preferably in the range 90-100 gsm. It comprises a lower clay coating27 with a base paper 29, with an upper clay coating 31. Thus, thesubstrate 19 comprises a carrier backing whilst substrate 17 comprisesthe stamp 1. Applied to the undersurface or back of the water-solublelayer 25 is a conventional pressure-sensitive adhesive 33. A siliconcoating 35 is applied over the clay coating 31 and thus, the stamp 1with the pressure-sensitive adhesive 33 can be releasably bonded to thesubstrate 19 on the silicon coating 35 thereon.

Referring now to FIG. 7 there is shown how a booklet of postage stampscan be produced. Here, stamp material 37 as described in relation toFIG. 6 is printed with a plurality of stamps 1 on one face. The stampswill have the luminescent coating applied thereto in the requiredarrangement so that each stamp 1 can be detected by a luminescencedetection apparatus. The stamps are severed by score lines 41 throughthe substrate 17 and the pressure-sensitive adhesive 33 but not throughthe silicon coating 35 or substrate 19. Thus, individual stamps 1 can bepeeled from the material 37 intact with the pressure-sensitive adhesiveon the rear face so they can be adhered to a postal article. Thematerial 37 is printed on the rear face--on the exposed face of thesubstrate 19--with any required markings. The material 37 can be foldedalong fold lines 43 to form a suitable booklet which can be easilycarried, thus, presenting the stamps 1 in a booklet form which resultsin a convenient means of selling stamps.

The inventive process of luminescent coating is equally applicable toconventional gum stamps to permit:

1. detection by luminescence detection devices;

2. the penetration and drying of approved stamp cancelling ink and thusthe invention is to be considered to clearly extend to such stamps. Byusing the luminescent coating as outlined herein less expensive paperscan now be used as the stamp paper.

Instead of the luminescent coating being a phosphor coating, it may be afluorescent coating material, such as a coating material similar to thatcurrently used by the Canadian Postal Authorities and which is appliedin solid areas and not in the arrangement contemplated in thisinvention.

Modifications may be made to the present invention as would be apparentto persons skilled in the stamp arts and/or printing arts and these areconsidered to be within the ambit of the invention the nature of whichis to be determined from the foregoing description.

We claim:
 1. A postage stamp comprising a stamp substrate which isfinish coated on a front face and having a stamp image on said frontface applied over the finish coating, an adhesive on a rear face, therebeing a luminescent coating printed over the front face of the stampover the finish coating over one or more areas which may include and beon said stamp image, said luminescent coating comprising a plurality ofcoated spaced regions interspersed with non-coated regions, theluminescent coating being of sufficient collective area relative to itsthickness and density to permit it to be detected by a postage stampluminescence detection device and the non-coated regions being ofsufficient area and distribution relative to the coated regions topermit penetration and drying of a stamp cancelling ink of a cancellingstamp and subsequent recognition of the cancelling stamp image as asubstantial whole if applied over said one or more areas.
 2. A postagestamp as claimed in claim 1 wherein the luminescent coating is appliedalong the length of the stamp.
 3. A postage stamp as claimed in claim 2wherein the luminescent coating is applied to a top of the stamp.
 4. Apostage stamp as claimed in claim 2 wherein the luminescent coating isapplied to a bottom of the stamp.
 5. A postage stamp as claimed in claim2 wherein the luminescent coating is applied to a top and to a bottom ofthe stamp.
 6. A postage stamp as claimed in claim 1 wherein theluminescent coating is applied along the width of the stamp.
 7. Apostage stamp as claimed in claim 6 wherein the luminescent coating isapplied to a left hand side of the stamp.
 8. A postage stamp as claimedin claim 6 wherein the luminescent coating is applied to a right handside of the stamp.
 9. A postage stamp as claimed in claim 7 wherein theluminescent coating is applied to a left hand side and to a right handside of the stamp.
 10. A postage stamp as claimed in claim 1 wherein theluminescent coating is applied in an area which extends over the wholeof the front face of the stamp and over said stamp image.
 11. A postagestamp as claimed in claim 1 wherein the luminescent coating extends overa selected region of the stamp image.
 12. A postage stamp as claimed inclaim 1 wherein the luminescent coating is applied as a phosphor varnishcoating and wherein over the one or more areas there is approximately80% of coating and approximately 20% non coating over a whitebackground.
 13. A stamp as claimed in claim 1 wherein the luminescentcoating is applied as a stipple coating.
 14. A stamp as claimed in claim1 wherein the adhesive is a pressure-sensitive adhesive.
 15. A stamp asclaimed in claim 14 wherein the pressure-sensitive adhesive is adheredto a release carrier backing so the stamp can be released from saidrelease carrier backing to be applied to a postal article.
 16. A stampas claimed in claim 14 wherein there is a water-soluble layer betweenthe stamp material and the pressure sensitive adhesive to permit thestamp to be recovered from a postal article by water dissolving of thewater-soluble layer by water penetration in areas which are not coatedwith a luminescent coating.
 17. A method or producing a postage stamp topermit detection by a postage stamp luminescence detection device and topermit penetration and drying of stamp cancelling ink comprising:(a)providing a stamp substrate which is finish coated on a front face; (b)providing a stamp image to said front face over the finish coating; (c)providing an adhesive on the rear face; (d) applying to the front faceof the stamp, after the stamp image is applied thereto, a luminescentcoating over one or more areas which may include and be on said stampimage so there are a plurality of coated spaced regions interspersedwith non-coated regions, the luminescent coating being of sufficientcollective area relative to its thickness and density to permit it to bedetected by a postage stamp luminescence detection device, and thenon-coated regions being of sufficient area and distribution to permitpenetration and drying of stamp cancelling ink of a cancelling stamp andsubsequent recognition of substantially the whole of the cancellingstamp image if applied over said one or more areas.
 18. A method asclaimed in claim 17 further comprising the step of applying theluminescent coating as a stipple.
 19. A method as claimed in claim 18wherein the stipple is applied as a series of dots in a regulararrangement.